1. Field of the Invention
The present invention relates to a fuel flow rate measuring device and method for measuring the flow rate of liquid fuel passing in a fuel supply inlet passage of a fuel tank, and an evaporated fuel treating device and method using the fuel flow rate measuring device. More particularly, the invention relates to a residual fuel quantity measuring device and method for determining the quantity of liquid fuel remaining in the fuel tank by measuring the quantity of liquid fuel supplied into the fuel tank and the rate of injection of liquid fuel into an internal combustion engine.
2. Description of Related Art
In automobiles mounted with a conventional gasoline engine, as shown in FIG. 14, at least one fuel pump 105 is disposed in a fuel tank 101 for forcing a liquid fluid (e.g., gasoline) from the fuel tank 101 to a fuel distribution pipe 104 having a plurality of fuel injection valves 103 for injecting the liquid fuel to the engine 102. In the plurality of fuel injection valves 103 and the fuel pump 105, the liquid fuel supply pressure, injection rate, and injection timing are automatically controlled by an engine ECU 106 in accordance with the operating conditions of the engine 102.
It has been a general practice that an automobile driver knows the remaining quantity of liquid fuel in the fuel tank 101 by a fuel meter 111 as a visual display which registers the remaining quantity of liquid fuel measured by a residual fuel quantity measuring device 100. The residual fuel quantity measuring device 100 is provided with at least one level gauge 107. The fuel meter 111 registers the residual quantity of liquid fuel according to an electric signal from the level gauge 107. A slide resistor of the level gauge 107 is connected via a float arm 109 with a float 108 which moves with a changing fuel level in the fuel tank 101, thus indicating a change in the electrical resistance value with the movement of the float 108.
The fuel tank 101, however, tends to be shaped in a more flattened and more complicated configuration as shown in FIG. 14 because of a restricted mounting space in the automobile. Consequently, a conventional residual fuel quantity measuring device 100, has a very low measuring accuracy in measuring the residual amount of liquid fuel remaining in the fuel tank 101 as compared with a measuring device for measuring the residual amount of liquid fuel in a fuel tank of a simple configuration.
The fuel tank in the complicated configuration, moreover, needs at least two level gauges 107 in the fuel tank 101 as shown in FIG. 14. Furthermore, such a fuel tank 101 of intricate configuration needs to further increase the number of the level gauges 107, resulting in an increased number of component parts of the residual fuel quantity measuring device 100 and accordingly a higher manufacturing cost of the residual fuel quantity measuring device 100.
When the fuel tank 101 is built in a more flattened or complicated configuration, it will become very hard to mount the level gauge 107 in the fuel tank 101, making it impossible to measure the remaining amount of liquid fuel in the fuel tank.
Also for the gasoline-powered automobile, there has been proposed the use of an evaporated fuel treating device (e.g., Japanese Utility Model Laid-Open No. Sho 60-158922, and Japanese Patent Laid-Open Nos. Hei 8-170568 and Hei 7-290982) for preventing the discharge into the atmosphere of the fuel evaporated in the fuel tank.
According to Japanese Utility Model Laid-Open No. Sho 60-158922 and Japanese Patent Laid-Open No. Hei 8-170568, the amount of evaporated fuel generated is restricted by covering, with a bag-like expansion film, the fuel in the fuel tank and a separation film which is in tight contact with the fuel surface in the fuel tank and moves up and down with the movement of the fuel surface.
In the evaporated fuel treating device having the separation film or bag-like expansion film, it is necessary to make a mounting hole for mounting the level gauge inside of the expansible film larger and accordingly it is necessary to make a sealing portion larger. However, if the sealing portion is made larger, sealing properties will be deteriorated to lower the effect of restraining the generated amount of evaporated fuel.
Furthermore, according to Japanese Patent Laid-Open No. Hei 7-290982, an electromagnetic valve is provided in a pipe connecting the fuel tank and a canister so that the valve opens at the time of refilling the fuel and the evaporated fuel in the tank is adsorbed by the canister.